US11931966B2

US11931966B2 - Systems and methods for optical assessments of bioink printability

Info

Publication number: US11931966B2
Application number: US16/964,899
Authority: US
Inventors: Patrick Thayer; Hany Abushall; Hector Martinez; Erik Gatenholm
Original assignee: Cellink Bioprinting AB
Current assignee: Cellink Bioprinting AB
Priority date: 2018-01-26
Filing date: 2019-01-25
Publication date: 2024-03-19
Also published as: WO2019145795A3; US20210031456A1; WO2019145795A2

Abstract

Systems and methods for optical assessments of bioink printability are described. The systems and methods include the use of hardware, software and optical targets to aid in the evaluation of bioink printability. The optical targets are developed and fabricated from 3D printable materials determined to be “nozzle fidelic” and/or materials that possess well characterized thermosensitivity. The optical targets make it possible to rapidly compare and evaluate bioink printability and can be easily customized and tailored for specific applications.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

- The present application is a National Stage application under 35 U.S.C. 371 of International Application No. PCT/IB2019/000215, filed Jan. 25, 2019, which application relies on the disclosure of and claims priority to and the benefit of the filing date of U.S. Provisional Application No. 62/622,650 filed Jan. 26, 2018, the disclosures of which are hereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to the fields of 3D printing and bioprinting. More particularly, embodiments of the present invention relate to optically-based systems and methods which allow for assessments of bioink printability.

Description of Related Art

A 3D bioprinter is a machine or device that spatially deposits, cross-links, or assembles biomaterials known as bioinks to fabricate tissue-like structures that are utilized in medical therapeutic, drug discovery, research, and tissue engineering fields. Bioprinters utilize materials known as bioinks to assemble multilayered three-dimensional structures or single layered two-dimensional patterns via extruded filaments, deposited droplets, or controlled crosslinking. Bioprinting utilizes 3D printing and 3D printing—like techniques to combine cells, growth factors, and biomaterials to fabricate constructs that maximally imitate natural tissue characteristics and can be utilized in applications such as drug evaluation and discovery, tissue and organ engineering, studying cells in a 3D environment, and recapitulating multifaceted native architectures.

The resulting characteristics of a bioink are highly dependent on both the bioink composition and the printing parameters utilized during the fabrication process. The overall quantification of the relationship between the resulting filament characteristics and the printing parameters is known as the printability of the bioink. Materials that are suitable for 3D bioprinting applications are distinct from traditional 3D printing materials. These materials, known as bioinks, can be defined by two qualities. The first is the ability to support and maintain cell viability during and after the printing process, the second is maintenance of structure and resulting filament characteristics after deposition and cross-linking (if applicable). As available bioinks increase there is a need for complementary techniques and metrics to validate a 3D bioprinted structure and bioinks.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide systems and methods for optical assessments of bioink printability. The systems and methods include the use of hardware such as bioprinter or 3D printer systems, optical imaging devices, and standardized or customizable optical targets to enable the evaluation of bioink printability. The optical targets are developed and fabricated from 3D printable materials for the establishment of comparison and calibration standards based on “nozzle fidelic” or other materials such as those with well characterized thermosensitivity, cross-linking behavior, stability, or other relative properties. The optical targets make it possible to rapidly compare and evaluate bioink printability and can be easily customized and tailored for specific applications.

Additional embodiments and their features will be elaborated in the foregoing Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a printhead of a 3D printer or bioprinter according to an embodiment.

FIG. 2 is a drawing of an ink/bioink pressure calibration process according to an embodiment.

FIG. 3 is a schematic drawing of an automatic feedback control according to an embodiment.

FIG. 4 is a flowchart of steps for an exemplary process according to an embodiment.

FIG. 5 is a flowchart of a method for ink/bioink characterization according to an embodiment.

FIG. 6 is a flowchart of a method for ink/bioink calibration according to an embodiment.

FIG. 7 is a flowchart of a printing process according to an embodiment.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

Reference will now be made in detail to various exemplary embodiments of the invention. It is to be understood that the following discussion of exemplary embodiments is not intended as a limitation on the invention. Rather, the following discussion is provided to give the reader a more detailed understanding of certain aspects and features of the invention.

Definitions:

The following definitions are provided to facilitate understanding of certain terms provided in this specification. For other terms not defined herein, the ordinary meaning as recognized by an ordinarily-skilled artisan should be applied.

Optical Imaging Apparatus: Optical imaging is the use of light as an investigational imaging technique for medical and other applications. Examples include optical microscopy, spectroscopy, endoscopy, scanning laser ophthalmoscopy, and optical coherence tomography. According to this disclosure, the optical imaging apparatus includes one or more sensors and/or cameras for capturing images and/or video.

Droplet: A droplet is a structure that is formed when a material, for example, a bioink, is extruded at a single location on the print surface. The printhead does not translate in the x-y plane (where the x-y plane is the print surface), only in the z-direction, if necessary. Depending on the composition of the bioink, the resultant shape is typically circular or eclipse in shape when observed from above with an eccentricity between 0 and 1, and a minimum volume of 1 nL. A droplet can also be deposit through contactless bioprinting or printing techniques such as the use of an inkjet printing mechanism or an electrical field.

Printed filament: A printed filament is a structure that is formed when a bioink is extruded across the print surface where the printhead translates along waypoints to result in a non-enclosed structure. The printhead translates in the x-y plane (where the x-y plane is the print surface), with the nozzle positioned above the surface in the z-axis at a height between 10% and 500% of the nozzle inner diameter. A printed filament structure typically has a minimum total length to width ratio of 1 and a maximum of 100000.

Geometric structure: A geometric structure is a structure that is formed when a bioink is extruded across the print surface during printhead translation along waypoints and intersects or contacts the existing structure to enclose an area. The printhead translates in the x-y plane (where the x-y plane is the print surface), with the nozzle positioned above the surface in the z-axis at a height between 10% and 500% of the nozzle inner diameter. These geometric structures have a minimum of 0 vertices and 1 edge and enclose an area. The angle between subsequent edges at vertices can range from 0.001 degree to 179.99 degrees.

Infill Pattern: An infill pattern is a structure that is formed when a bioink is extruded across a print surface during printhead translation along waypoints in a fashion to fill in a printed geometric shape. The printhead translates in the x-y plane (where the x-y plane is the print surface), with the nozzle positioned above the surface in the z-axis at a height between 10% and 500% of the nozzle inner diameter. The infill pattern typically provides structural support, porosity, or generates micro-architectures that mimic native tissue structure or serve as a framework for tissue regeneration. The spacing between the centers of adjacent filaments (x-y positioning on the print surface) can range from a distance equal to the filament diameter to 5 times, 10 times, or 100 times the filament diameter. For example, for a 150 μm filament, the spacing between the centers of adjacent filaments can be 150 μm, up to 0.75 mm, up to 1.5 mm, or up to 15 mm. Infill pattern can also include multiple material or bioink types that are arranged or encapsulated within the broader structure. Deposited filaments such as those composed of sacrificial materials such as PEO (poly(ethylene oxide)), PEG (poly(ethylene glycol)), Pluronics® (poloxamers), and/or gelatin based bioink, can be used. Sacrificial materials which dissolve or are otherwise not permanent or present in the final structure are useful, for example, for creating void regions, conduits, and/or perfusable channels and can also be considered an infill pattern. These sacrificial materials may comprise 0% to 100% of the infill pattern, such as from 5-90%, or 15-75%, or 30-60%, or 10-80%, or 20-50%, for example.

Multilayered Structure: A multilayered structure is a structure that is generated when a bioink is extruded on top of a previously deposited structure. The printhead translates in the x-y plane (where the x-y plane is the previously deposited structure), with the nozzle positioned above the previously deposited structure in the z-axis at a height between 10% and 500% of the nozzle inner diameter. Droplets, printed filaments, geometric shapes, and infill patterns can all be printed on the previously printed layer. The number of previously printed layers is a minimum of 1 to achieve the maximum build height set by the bioprinter system being utilized.

Bioink printability: The overall quantification of the relationship between the resulting filament characteristics and the printing parameters is known as bioink printability. The resulting characteristics of a bioink are highly dependent on both the bioink composition and the printing parameters utilized during the fabrication process. These defined metrics can be utilized to compare and contrast different types of bioinks and printing conditions of bioinks.

Printability metrics of bioinks: Printability metrics of bioinks can include the resultant filament thickness, uniformity, roughness, continuity, color, opacity, and geometry at intersections and other directional changes that is quantifiable during and after the printing process and directly related to the utilized printing parameters.

Printing parameters of bioinks: Printing parameters of bioinks include applied pressure, strain, force, or flow, translation rate, start delay, stop delay, overshoot, undershoot of the printhead during the printing process, temperature of the bioink, temperature of the print surface, material of the print surface, layer height, infill pattern and density, the nozzle diameter, nozzle shape, and nozzle material.

Nozzle fidelic: A nozzle fidelic material is a bioink that can generate a stable filament with a diameter between 100% and 125% of the nozzle inner diameter. For example, a bioink capable of producing a filament of 500 μm from a nozzle with a 400 μm inner diameter is considered a nozzle fidelic material for that particular nozzle and conditions.

Real-time mode: In real-time mode, the system processes and compares the data captured by the optical imaging apparatus to the reference data already present in the system and/or the information provided by the user of the 3D bioprinter in actual time or within milliseconds of capturing the image and/or live video feed.

Layer-by-layer mode: In layer-by-layer mode, the system processes and compares the data captured by the optical imaging apparatus to the reference data already present in the system and/or the information provided by the user of the 3D bioprinter after a layer of the 3D build has been printed.

Process Algorithms: A process algorithm is any algorithm or protocol that receives an image or video from the optical imaging apparatus and identifies a point of interest, isolates it, and quantifies various metrics.

Learning Algorithms: A learning algorithm is any algorithm that receives data from or during a measurement and utilizes data from a broader dataset to automatically improve the existing print or future prints.

Database: A database is a repository of data consisting of bioink printability and properties, results of previous prints, and previous print adjustments that can be accessed by and shared across individual bioprinter systems to provide reference points and aid in the development of process and/or learning algorithms.

Printing Instructions: Printing instructions are computer code or computer-executable instructions which can include G-code files, STL files, text files, or manual inputs.

Microwell Plate: A microwell plate is a flat plate with more than one well used as small test tubes. It is typically used in analytical research and clinical diagnostic testing laboratories.

Embodiments of the present invention provide systems and methods for optical assessments of bioink printability. In one embodiment, a 3D printer or bioprinter system is provided that includes a plurality of components that work in concert to optically characterize one or more printability metrics of the 3D printer or bioprinter.

Provided is a 3D printer or bioprinter comprising one or more of the following:

(a) one or more optical imaging apparatus;

(b) one or more control element;

(c) one or more processor and communication interface operably connecting and capable of communicating printability data from the one or more optical imaging apparatus to the one or more control element; and

(d) a non-transitory computer-readable storage media comprising:

(1) one or more process algorithms capable of analysis of the printability data from one or more images and/or video of a first printed structure produced by the 3D printer or bioprinter; and

(2) optionally, one or more learning algorithms capable of modifying and adjusting printing instructions and/or parameters based on one or more printability metrics to achieve a second printed structure.

According to embodiments, the 3D printer or bioprinter can include one or more additional components such as motors, printheads, print bed, substrates for printing, printed structures, cartridges, syringes, platforms, lasers, operating controls, power cables, and USB ports/connectors and/or cables.

According to embodiments, the 3D printer or bioprinter is in communication with or integrated with a database where printability analysis can be shared and compared across batches and users.

According to embodiments, the optical imaging apparatus includes one or more infrared, near-infrared, visible, or UV sensors or cameras. The imaging apparatus can be capable of obtaining high definition (HD) images, such as HD digital images.

In embodiments, the imaging apparatus can be mounted to a printhead, whether a single-function or multi-function printhead. As shown in FIG. 1 , the imaging apparatus can comprise an HD camera mounted to the side of one or more printhead that is or is not also capable of printing bioink. The camera can be disposed in a position where the optical elements of the camera are oriented toward the print bed of the 3D printer or bioprinter, or other printing surface. In this manner, the camera can obtain still and/or video images of the print bed or printing surface and/or the structure being formed on the print bed or printing surface, before, during or after the printing. In embodiments, the imaging apparatus is disposed on a printhead in a manner such that the imaging apparatus is positioned to the side, above, and/or below the nozzle of the printhead through which bionk is disposed during the printing process. The still and/or video images captured by the camera can be transmitted back to a processing and/or control unit located inside and/or outside the 3D bioprinter. In principle, one or more than one camera can be mounted in and/or on any part of the printhead.

According to embodiments, the one or more printability metrics can be chosen from one or more of filament thickness, uniformity, roughness, continuity, color, opacity, and/or geometry at intersections and/or other directional changes.

According to embodiments, the printing parameters can be chosen from one or more of applied pressure, strain, force, or flow, printhead translation rate, bioink temperature, bioink composition, print surface temperature, layer height, infill pattern and density, nozzle diameter, nozzle shape, and/or nozzle material.

A calibration process according to embodiments of the invention is shown in FIG. 2 . The 3D printer or bioprinter is programmed to deposit a bioink under both variable and constant printing parameters. For this example, all parameters will be held constant with the exception of printing pressure and translation rate. The user provides printing instructions or the 3D printer or bioprinter generates printing instructions from user input or an algorithm that varies a particular printing parameter. The printing instructions deposit filaments that are generated from distinct parameters. The bioprinter or 3D printer then utilizes the optical imaging apparatus to capture an image. These are then presented to the user and/or entered into a processing and/or learning algorithm for evaluation as a whole, which algorithm(s) then recommend optimal parameters for the desired resulting diameter or other characteristic.

According to embodiments, the printed structure is or includes a droplet, a linear or curved filament, a geometric shape, an infill pattern, and/or multilayered structure deposited using a bioink. In combination with the printer elements, the printed structured can serve as an optical or calibration target to allow rapid comparisons to known standard printable materials and/or internal controls.

For example, the optical or calibration target can be or can include a non-thermoresponsive filament, a thermoresponsive filament, or both. In addition or alternatively, the optical or calibration target can be or can be comprised of “nozzle fidelic” printable materials, such as thermoplastics or silicone so the user can fabricate customizable printability targets. Examples of suitable thermoplastics include polyethylene, polypropylene, polyvinyl chloride (PVC), and polystyrene. Further, the optical or calibration target can be or can include materials that exhibit a well characterized thermosensitivity as a calibration target which can be analyzed using software and thermal sensors or cameras such as infrared-detecting sensors and/or cameras. Still further, the printability data generated from the calibration target using such materials can be used to calibrate the printing parameters and adjust the printing instructions, such as provided by G-code, to optimize printing.

According to embodiments, printing instructions which include G-code files, STL files, text files, or manual inputs can be provided by the user or generated through software.

According to embodiments, the optical imaging apparatus can be provided as an independent printhead that does not deposit bioink and/or the structure that is being analyzed. In embodiments, the optical imaging apparatus can be provided as an independent printhead that does deposit bioink and/or the structure that is being analyzed.

According to embodiments, the optical imaging apparatus includes one or more cameras or video cameras attached to a printhead that is depositing the structure that is currently being imaged. In embodiments, the optical imaging apparatus can comprise multiple cameras or video cameras disposed on one or more printheads (which may or may not be the printhead(s) depositing material for the structure that is being imaged or analyzed). For example, the optical imaging apparatus can include at least two cameras offset to capture stereographic images. The camera, video camera, or multiple cameras or video cameras can be disposed on the same or different printheads or at another location within or in the proximity of the 3D printer or bioprinter. The imaging apparatus can comprise one or more illumination source and/or one or more illumination source can be included with the 3D printer or bioprinter to provide illumination for the imaging apparatus. As shown in FIG. 3 , the illumination source(s), such as a light source, can be mounted on one or more printheads of the 3D printer or bioprinter in a manner to provide light for imaging placement of bioink on a print bed. In embodiments, the illumination source(s) can provide light having an illumination angle of up to 30 degrees, up to 45 degrees, up to 60 degrees, up to 90 degrees, up to 120 degrees, up to 180 degrees or more. In addition, the illumination sources can provide any single or combination of light colors and wavelengths for the illumination of the sample and/or bioink filaments. The illumination sources can be used to illuminate sample(s), microwell plate(s), 2D printed layer(s) and/or 3D printed structures.

According to embodiments, the optical imaging apparatus is able to capture images or videos before, during, and/or after printing, such as in real-time during the printing.

According to embodiments, the process or analysis algorithm receives and analyzes images or video captured from the imaging apparatus, which data and images can be captured and analyzed after printing all or some of the structure, such as in real-time. The analysis algorithm can utilize information from visual sensors to identify, isolate, and/or quantify the characteristics of the deposited structure before, during, or after some or all of the printing process. The process or analysis algorithm can also utilize information from visual sensors to identify, isolate, and/or quantify the characteristics of the deposited structure before, during, or after completion of one or more printed layer or each printed layer, such as in real-time.

According to embodiments, the learning algorithm facilitates machine learning so that the 3D printer or bioprinter can quantify, compare, and/or adjust the printing instructions based on the measured printed structure characteristics in real-time or before or after the completion of a printed layer or each printed layer. As a result, a better printed structure is generated by altering some, any and/or all of the printing parameters of the 3D printer or bioprinter in order to deposit ink, such as bioink, such as a filament or whole printed structure, that more closely resembles the structure defined by the user through the printing instructions.

In embodiments, the learning algorithm compares what is measured to what has previously been measured with other prints and adjusts the parameters respectively or makes recommendations on how to adjust the parameters. The learning algorithm can also be used to recommend new ink/bioink compositions based on some or all the data that has been collected (big data analysis). Additionally, the learning algorithm can also be used to determine the ideal printability parameters of a bioink with an unknown composition or a new composition that has yet to be tested.

According to embodiments, the learning algorithm can be a classification algorithm such as hierarchical clustering, k means clustering, linear discriminant analysis, logistic regression, support vector machines, k-nearest neighbor, recursive partitioning, decision trees, neural networks, Bayesian networks, and Hidden Markov models.

According to embodiments, the database integration permits the utilization of printability metrics from other users and/or the manufacturer. The printability metrics can be obtained from an external database and/or the manufacturer, from an incorporated barcode, or from an RFID chip within the packaging of the 3D printer or bioprinter or parts thereof, such as a barcode on a bioink cartridge.

According to embodiments, the 3D printer or bioprinter can be integrated with or incorporates clean chamber technology or a clean chamber housing which provides sterility during the printing process as described in International Patent Application Publication No. WO 2017/040675, US2010/0206224, 2017/0172765, 2015/0105891, 2009/003696, 2012/024675, RE43955, U.S. Pat. No. 7,894,921, WO2009/053100, U.S. Pat. Nos. 7,892,474, 8,394,313, 7,783,371, 7,636,610, 7,195,472, 7,052,263, 6,942,830, WO2008/055533, EP1732746, US2017/0225393, US2017/0100899, US2017/0080641, US2015/0246482, US2015/0102351, U.S. Pat. No. 9,073,261, each incorporated by reference herein in their entireties.

According to embodiments, the 3D printer or bioprinter can utilize a cellulose nanofibrillar dispersion as bioink as described in United States Patent Application Publication No. 20170368225, incorporated by reference herein in its entirety.

Embodiments of the invention include methods of generating printing characteristics associated with various printing parameters for an ink or bioink. The flowcharts provided in FIGS. 4 and 7 provide examples of such methods. As shown in FIG. 4 , the user selects an ink or bioink and inputs parameters associated with the ink or bioink into the printing program, such as printing pressure, extrusion rate, translation rate, layer height, printhead temperature, printbed temperature, and/or type of ink/bioink. Additionally or alternatively, printing parameters and other data can be imported from a cloud server or other external method. The central processing unit (CPU) sends Gcode and parameters to the printheads. The printheads fabricate a 3D structure from the ink or bioink according to the Gcode and/or other parameters if provided. The imaging apparatus images the printed structure during and/or after the print and the image(s) are transferred to the CPU for analysis, for example, using processing and learning algorithms. The CPU displays the results to the user and the inputs can be changed if desired. Subsequent prints can be performed and/or the printing parameters and/or printing data can be transferred to a database for future use and quality control. As shown in FIG. 7 , the user and/or the computer selects printing parameters. The 3D structure is printed in accordance with instructions implementing the printing parameters. The structure is imaged using a camera, such as an HD camera. Analysis of the printed structure is performed to determine characteristics of the printed structure. The characteristics of the printed structure are compared with standards and/or previous data obtained through prior printing processes. The computer can recommend various changes to the printing parameters to obtain a printed structure that is closer in comparison with the standards and/or other previously obtained data. The printing process can then be repeated and/or the printing parameters changed based on the analysis and then the printing process can be repeated until a desirable final printed structure is obtained.

Another embodiment comprises a method for assessing printability of a bioink. The method can include any of the following steps:

- (a) selecting one or more bioink, one or more printing parameters, and one or more printed structure characteristics;
- (b) depositing the one or more bioink based on the selecting of the one or more bioink, the one or more printing parameters, and the one or more printed structure characteristics to create a first deposited structure;
- (c) imaging the first deposited structure by one or more optical imaging apparatus to provide an optical image of the first deposited structure;
- (d) analyzing the optical image by way of one or more algorithms;
- (e) adjusting the printing parameters based on the analysis; and
- (f) depositing a second deposited structure based on the adjusting.

In assessing printability of bioinks, the 3D printer or bioprinter can compare the printed bioink to previously tested inks or bioinks and/or batch standards, and physically calibration targets that contain premade structures with ‘ideal’ diameters and shapes.

According to embodiments, one or more of the optical imaging, analysis, and/or adjustment of printing parameters and/or instructions can be repeated until a defined printed structure is achieved with satisfactory accuracy.

According to embodiments, the selection of bioink can be from preset bioink profiles that are loaded by a user or from an external database.

According to embodiments, the selection of printing parameters can be from a preset profile, loaded or adjusted by a user, or from an external database.

According to embodiments, the selection of the printed structure can be from a preset profile, loaded or adjusted by the user, or from an external database.

According to embodiments, the one or more algorithms can automatically modify and/or adjust the bioink profiles, printing parameters, and/or printed structure characteristics.

In embodiments, the algorithm(s) can compare the measured/imaged parameters to previously tested inks, the batch standards, and/or physical calibration targets that contain premade structures with ‘ideal’ diameters and shapes.

According to embodiments, adjustment of the printing instructions can include the positioning of the optical apparatus to permit imaging of the deposited structure.

According to embodiments, the analysis can be performed before, during, or after printing, such as in real-time, and the printing instructions are capable of being modified before, during, or after the print.

According to embodiments, the results of the analysis can be compiled in a database where such results are utilized to refine subsequent analysis.

Another embodiment provides a method for calibration of a bioink on a 3D printer or bioprinter. The method can include any of the following steps:

- (a) providing a calibration target on a surface or fabricating a calibration target on a surface using a 3D printer or bioprinter;
- (b) fabricating a bioink structure;
- (c) imaging and preparing an image of the bioink structure and the calibration target;
- (d) analyzing the image of the bioink structure and the calibration target by way of one or more algorithms; and
- (e) adjusting one or more printing parameters based on the analyzing.

According to embodiments, the surface includes a print surface or a separate surface within the 3D printer or bioprinter or inserted into the 3D printer or bioprinter.

According to embodiments, the analyzing involves assessing one or more of filament thickness, uniformity, roughness, continuity, color, opacity, and/or geometry at intersections and/or other directional changes in comparison with the calibration target.

According to embodiments, the printing parameters are chosen from one or more of applied pressure, strain, force, or flow, printhead translation rate, bioink temperature, bioink composition, print surface temperature, layer height, infill pattern and density, nozzle diameter, nozzle shape, and/or nozzle material.

According to embodiments, the one or more calibration targets include patterned arrangements of droplets, filaments, geometric shapes, infill patterns, and/or multilayered structures.

According to embodiments, the one or more calibration targets are fabricated and customized based on input of a user or designation of integrated software and algorithms of the 3D printer or bioprinter.

According to embodiments, the separate surface includes one or more different materials including plastic, glass, hydrogel, or biomolecule coated surfaces to calibrate the one or more printing parameters on different surfaces.

According to embodiments, the one or more calibration targets are fabricated based on previous printability metrics and analysis performed and recommended by learning algorithms to more rapidly test a bioink.

For example, using a calibration target is a quick way to compare a filament or shape with an ideal filament or shape. In one iteration, the calibration target may have lines with diameters of 200 μm, 400 μm, 600 μm, 800 μm, etc. The user can quickly print a line, then compare the line to the targets. The comparison, for example, may involve comparing the printed bioink to the calibration target to determine if the bioink is printed with the same height and shape as the calibration target. This allows the user to quickly figure out how the material is printing initially so when the algorithm begins to optimize it knows what range of possible printing parameters to start at based on previous data. For example, if a user desires to print a line that is 450 μm in diameter, the objective is 500 μm. So the user knows that whatever parameters are desired to be tested should be between the parameters just used to achieve a 450 um diameter line and the parameters observed in the past to achieve a 600 μm line. The algorithm can be programmed to start homing down in that range.

According to embodiments, the fabrication of the bioink structure occurs adjacent to or in proximity of the one or more calibration targets for rapid analysis.

According to embodiments, one or more prefabricated calibration targets are provided to contain a range of filament diameters, heights, intersection angles along with geometric structures, and multilayered structures with various infill patterns and porosity.

According to embodiments, the one or more printing parameters are stored within the 3D printer or bioprinter and in a database on a per batch basis and are capable of serving as a quality control comparison point.

According to embodiments, the system can include a non-transitory computer storage media such as RAM which stores a set of computer-executable instructions (also referred to herein as computer-readable code, “code”, or software) for instructing the processor(s) to carry out any of the algorithms and methods described in this disclosure. As used in the context of this specification, a “non-transitory computer-readable medium (or media)” may include any kind of computer memory, including magnetic storage media, optical storage media, nonvolatile memory storage media, and volatile memory. Non-limiting examples of non-transitory computer-readable storage media include floppy disks, magnetic tape, conventional hard disks, CD-ROM, DVD-ROM, BLU-RAY, Flash ROM, memory cards, optical drives, solid state drives, flash drives, erasable programmable read only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), non-volatile ROM, and RAM. The non-transitory computer readable media can include one or more sets of computer-executable instructions for providing an operating system as well as for implementing the algorithms and methods of the invention. The computer-executable instructions can be programmed in any suitable programming language, including JavaScript, C, C#, C++, Java, Python, Perl, Ruby, Swift, Visual Basic, and Objective C.

EXAMPLES

An example of a process algorithm may include the following steps. First a structure is deposited by a 3D printer system on a print surface. The parameters utilized to print the structure which may include applied pressure, strain, translation speed, nozzle shape, nozzle diameter, layer height, temperature of printhead and/or printbed can be recorded by the system. The structure is then imaged during or after the completion of the printing process. The image can be inputted into the process algorithm. The process algorithm filters out the background and isolates the region of interest. In this example, the region of interest may be a linear filament, but it can be any structure. After finding the region of interest, the application determines the boundaries of the filament or structure. The data on the location of these boundaries is extracted and then processed to quantify characteristics of the filament or structure such as diameter, uniformity, thickness, etc. This data is then presented to the user so the user can adjust the printing parameters based on the result and refine the printing process, if needed. Additionally, this data can be stored on the printer or uploaded to a database where it can refine other algorithms. See for example FIGS. 4 and 7 .

An example of a learning algorithm may include the following steps. In this example, the learning algorithm is used to calibrate a bioink in real-time by comparing it to a standard and historical printing data. The user chooses the desired resulting structural characteristics. Based on previous data, the algorithm sets default printing parameters and then prints a structure. The algorithm then compares the characteristics of the resulting structure to the standard. The standard could be the theoretical ideal printing result or a calibration target that has a predefined structure that the print wants to achieve. Based on previous prints during this process, the current printing parameters, and/or the bioink composition, the algorithm predicts how the printing parameters should be adjusted to achieve the desired characteristics. This process can be repeated until the printing parameters that are recommended provide a structure within an acceptable error of the target. See, for example, FIG. 6 , where a user inserts a bioink whose parameters will be calibrated, and the desired filament diameter is set by the user. The learning algorithm sets predicted printing parameters. The user inserts an appropriate calibration target and Gcode is generated to print a structure onto the calibration target. Then an image(s) of the printed structure is captured using a camera printhead and the image is analyzed using one or more process algorithm according to the invention. Additionally, one or more learning algorithms can be used to compare the analyzed structure to reference data, such as previous print data and/or stored data relating to other prints. New printing parameters can be set and associated Gcode provided for performing the printing using the new printing parameters. The printing and analysis steps can be repeated any number of times until the desired/target filament diameter is obtained. The printing parameters can be output to a database to be used later as a reference for parameters recommended and/or suggested for obtaining the desired/target filament diameter for that bioink.

Another example of a learning algorithm may include the following process. In this example, the learning algorithm is used to preset printing parameters based on the composition of the bioink that is provided by the user and/or other source. The user inputs data that relates to the composition of the bioink they want to print with, if known. The inputted data can include chemical base, concentration, composition, and/or type of material. The learning algorithm compares this bioink to previous bioink characteristics obtained, for example, from a reference source and/or previous prints and gives recommended printability data for the bioink. Gcode can be generated to change printing parameters for evaluation. The bioink calibration process can follow the steps in the above learning algorithm example to print a 3D structure, image the structure, analyze features of the structure, and compare the structure with other reference structures and/or previously printed structures. Alternatively, the algorithm can analyze one or more or all the printability data for one or more or all the bioinks as a whole and make recommendations for new bioinks or improvements in currently used bioinks regarding printability and composition. See, for example, FIG. 5 .

The present invention has been described with reference to particular embodiments having various features. In light of the disclosure provided above, it will be apparent to those skilled in the art that various modifications and variations can be made in the practice of the present invention without departing from the scope or spirit of the invention. One skilled in the art will recognize that the disclosed features may be used singularly, in any combination, or omitted based on the requirements and specifications of a given application or design. When an embodiment refers to “comprising” certain features, it is to be understood that the embodiments can alternatively “consist of” or “consist essentially of” any one or more of the features. Any of the methods disclosed herein can be used with any of the systems or devices disclosed herein or with any other systems or devices. Likewise, any of the disclosed systems or devices can be used with any of the methods disclosed herein or with any other methods. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention.

It is noted in particular that where a range of values is provided in this specification, each value between the upper and lower limits of that range is also specifically disclosed. The upper and lower limits of these smaller ranges may independently be included or excluded in the range as well. The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. It is intended that the specification and examples be considered as exemplary in nature and that variations that do not depart from the essence of the invention fall within the scope of the invention. Further, all of the references cited in this disclosure are each individually incorporated by reference herein in their entireties and as such are intended to provide an efficient way of supplementing the enabling disclosure of this invention as well as provide background detailing the level of ordinary skill in the art.

Claims

The invention claimed is:

1. A 3D bioprinter comprising:

(a) one or more printheads and one or more optical imaging apparatus disposed on one or more of the printheads in a manner such that the optical imaging apparatus is positioned to the side, above and/or below a nozzle and is capable of capturing images or video of bioink dispensed from the nozzle during printing;

(b) one or more control element;

(c) one or more processor and communication interface operably connecting and capable of communicating printability data from the one or more optical imaging apparatus to the one or more control element to control printing of a printed structure; and

(d) a non-transitory computer-readable storage media comprising:

(1) one or more process algorithms capable of quantifying printing characteristics chosen from one or more of shape, uniformity, thickness, size, and/or color of droplets or filaments of the bioink disposed from the nozzle from one or more images and/or video obtained with the optical imaging apparatus; and

(2) one or more learning algorithms capable of modifying and adjusting printing instructions and/or printing parameters based on one or more printability metrics to modify the printed structure in real time and before completion of the printing.

2. The 3D bioprinter of claim 1, wherein the one or more printability metrics are chosen from one or more of filament thickness, uniformity, roughness, continuity, color, opacity, and/or geometry at intersections and/or other directional changes.

3. The 3D bioprinter of claim 1, wherein the printing parameters are chosen from one or more of applied pressure, strain, force, or flow, printhead translation rate, bioink temperature, bioink composition, print surface temperature, layer height, infill pattern and density, nozzle diameter, nozzle shape, and/or nozzle material.

4. The 3D bioprinter of claim 1, wherein the one or more optical imaging apparatus is fixed or detachable.

5. The 3D bioprinter of claim 1, comprising one or more additional components chosen from motors, one or more print beds, one or more substrates for printing, one or more additional printed structures, one or more syringes, one or more platforms, one or more lasers, one or more operating controls, one or more power cables, and/or one or more USB cables.

6. The 3D bioprinter of claim 1, wherein the 3D bioprinter is in communication with or integrated with a database.

7. The 3D bioprinter of claim 1, wherein the 3D bioprinter is in communication with or integrated with a database for storing one or more printability analysis.

8. The 3D bioprinter of claim 1, wherein the 3D bioprinter is in communication with or integrated with a database for storing one or more printability analysis, which printability analysis is capable of being shared and compared across batches and users.

9. The 3D bioprinter of claim 1, wherein the one or more optical imaging apparatus comprises one or more infrared, near-infrared, visible, and/or UV sensors or cameras.

10. The 3D bioprinter of claim 1, wherein the printed structure is capable of serving as an optical or calibration target.

11. The 3D bioprinter of claim 1, wherein the printed structure is capable of serving as an optical or calibration target to allow rapid comparisons to known standard printable materials and internal controls.

12. The 3D bioprinter of claim 1, wherein the printed structure is capable of serving as an optical or calibration target and comprises one or more materials that are capable of being analyzed by software and thermal sensors or cameras including infrared-detecting sensors and/or cameras.

13. The 3D bioprinter of claim 1, wherein the printed structure which serves as an optical or calibration target comprises one or more of non-thermoresponsive filament, thermoresponsive filament, nozzle fidelic printable material, nozzle fidelic printable material chosen from thermoplastics or silicone, and/or materials that exhibit thermosensitivity.

14. The 3D bioprinter of claim 1, wherein the printing instructions comprise one or more of G-code files, STL files, text files, and/or manual inputs, wherein the manual inputs are capable of being provided by a user or generated through software.

15. The 3D bioprinter of claim 1, wherein the one or more optical imaging apparatus comprises one or more cameras and is disposed on one or more of the printheads that is an independent printhead not capable of depositing bioink.

16. The 3D bioprinter of claim 1, wherein the one or more optical imaging apparatus comprises one or more cameras and is disposed on one or more of the printheads that is capable of depositing material.

17. The 3D printer of bioprinter of claim 1, wherein the one or more optical imaging apparatus comprises at least two cameras disposed in a manner to capture one or more stereographic images.

18. The 3D bioprinter of claim 1, wherein the one or more optical imaging apparatus is capable of capturing images or videos in real-time during printing or post printing.

19. A 3D bioprinter comprising:

(a) one or more printheads and one or more optical imaging apparatus disposed on one or more of the printheads in a manner such that the optical imaging apparatus is positioned to the side, above, and/or below a nozzle and is capable of capturing images or video of bioink dispensed from the nozzle during printing;

(b) one or more control element;

(d) a non-transitory computer-readable storage media comprising:

(2) one or more learning algorithms capable of i) calibrating a bioink and ii) modifying and adjusting printing instructions and/or printing parameters based on one or more printability metrics to achieve a second printed structure.

20. The 3D bioprinter of claim 19, wherein the one or more learning algorithms capable of calibrating of the bioink are configured to compare imaging of the bioink against a calibration target.

21. The 3D bioprinter of claim 19, wherein one or more of the optical imaging apparatus, the one or more control element, the one or more process algorithms, and the one or more learning algorithms together are capable of calibrating the bioink by:

(a) depositing the one or more bioink under both variable and constant printing parameters;

(b) capturing an image of the deposited bioink;

(c) evaluating the image; and

(d) recommending one or more optimal printing parameter for the bioink.

22. The 3D bioprinter of claim 19, wherein the one or more learning algorithms are capable of recommending one or more optimal printing parameter for the bioink based on a captured image of deposited bioink.